The University of North Carolina at Chapel Hill and the Society for Occupational and Environmental Health are jointly sponsoring an international symposium entitled "Silica, Silicosis and Cancer." The symposium is planned for April 3-5, 1984, in Chapel Hill, North Carolina. The rationale for convening this symposium is that there is now evidence that silica may act as a carcinogen. Silica has heretofore been considered a fibrogenic dust that causes silicosis, the sequelae of silicosis, and an old occupational disease whose incidence is declining. If silica may be a carcinogen (alone or combined with other hazardous materials), the concern is that there is a range of between 520,000 and 3,200,000 workers potentially exposed. Some of the occupations include auto workers, cement workers, ceramic workers, construction workers, foundrymen, glass makers, granite workers, metal ore miners, masons, quarrymen, sandblasters, silica brick workers, and tunnel builders. Recent experimental animal evidence suggests that silica alone produces pulmonary histiocytic lymphomas and lung tumors. These experimental results support the findings of lung and gastrointestinal cancer excesses observed among workers who it is assumed were highly exposed to silica and other particulates. Despite the general lack of industrial hygiene measures to confirm the effect of silica exposure, lung cancer excesses have been reported for the following occupations: gold and metal ore miners, foundry workers, sandblasters, silica firebrick makers, ceramicists, and granite workers. Miners, foundrymen, and granite workers also have elevated risks for gastrointestinal cancers. Of special note are the striking relative risks between three and six for lung cancer in two followup studies of silicotics in Sweden and Canada. Swedish researchers have recently confirmed their initial result with a new casecontrol study of lung cancer among silicotics. Leadings researchers in this field will be invited to address the Symposium. In addition, presentations of new findings will be made based on a blinded review of abstracts. We anticipate that the Symposium and publication of the proceedings will permit scientists in this wide field to share common intellectual ground, thus permitting new research endeavors to be undertaken.